Definition: Given a passage with a context and an answer, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.
Input: Context: Endoscopic surveillance for adenocarcinoma in patients with Barrett's esophagus is costly, with one cancer detected every 48-441 patient years of follow up. Genetic abnormalities, including loss of heterozygosity at sites of tumor suppressor genes, have been detected in malignant and premalignant Barrett's esophagus. The aim of this prospective study was to determine if loss of heterozygosity analysis could identify patients with Barrett's esophagus at greatest risk of adenocarcinoma, for whom endoscopic surveillance is most appropriate.", "Loss of heterozygosity analysis was performed on endoscopic biopsies from 48 patients as part of a Barrett's surveillance program using 14 microsatellite markers shown previously to detect loss of heterozygosity in more than 30% of esophageal adenocarcinomas. Patients were followed up endoscopically for a median of 5 years.", 'Loss of heterozygosity was detected in nine patients. Three patients with loss of heterozygosity on chromosome 5q or 9p did not progress beyond metaplasia. Loss of heterozygosity at 17p11.1-p13 was detected in six patients, all of whom demonstrated dysplasia and/or carcinoma during follow up (four low-grade dysplasia, one high-grade dysplasia and one adenocarcinoma).
Answer: Loss of heterozygosity at 17p11.1-p13 on chromosome 17p identifies patients with Barrett's esophagus at risk of neoplastic progression and can supplement histology in determining the frequency of endoscopy during surveillance.

Does loss of heterozygosity on chromosome 17p predict neoplastic progression in Barrett 's esophagus?